Theatrical fog particle protection system for image projection lighting devices

ABSTRACT

An image projection lighting device is disclosed comprising a base housing, a yoke, and a lamp housing. The base housing may include or have located therein, a processing system and a communications port. The lamp housing may include or have located therein, a video projector, an antireflective aperture, a cooling system, and an air filter system. The image projection lighting device may further include a multicolor video display device, which may display a signal indicating a service alert, such as a filter service alert. Service information, concerning the image projection lighting device, may be transmitted by the image projection lighting device from the communications port to a central controller.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation in part of and claims thepriority of U.S. patent application Ser. No. 10/360,185, titled “ImageProjection Lighting Device” filed on Feb. 7, 2003. Note that thispresent application, if possible, does not claim the priority of anyprior patent application, such as the applications, the priority ofwhich is claimed in Ser. No. 10/360,185. If this is not possible, thenthe present application does not claim the priority of any application.

FIELD OF THE INVENTION

The present invention relates to image projection lighting devices.

BACKGROUND OF THE INVENTION

Lighting systems in the prior art are typically formed byinterconnecting, via a communications system, a plurality of lightingfixtures and providing for operator control of the plurality of lightingfixtures from a central controller. Such lighting systems may containmultiparameter light fixtures, which illustratively are light fixtureshaving two or more individually remotely adjustable parameters such asfocus, color, image, position, or other light characteristics.Multiparameter lighting fixtures are widely used in the lightingindustry because they facilitate significant reductions in overalllighting system size and permit dynamic changes to the final lightingeffect. Applications and events in which multiparameter lightingfixtures are used to great advantage include showrooms, televisionlighting, stage lighting, architectural lighting, live concerts, andtheme parks. Illustrative multi-parameter light devices are described inthe product brochure entitled “The High End Systems Product Line 2001”and are available from High End Systems, Inc. of Austin, Tex.

A variety of different types of multiparameter light fixtures areavailable. One type of advanced multiparameter lighting fixture is animage projection lighting device (“IPLD”). Image projection lightingdevices of the prior art typically use a light valve or light valves toproject images onto a stage or other projection surface. A light valve,which is also known as an image gate, is a device for example such as adigital micro-mirror (“DMD”) or a liquid crystal display (“LCD”) thatforms the image that is projected. Either a transmissive or a reflectivetype light valve may be used. U.S. Pat. No. 6,057,958, issued May 2,2000 to Hunt, incorporated herein by reference, discloses a pixel basedgobo record control format for storing gobo images in the memory of alight fixture. The gobo images can be recalled and modified fromcommands sent by a control console. A pixel based gobo image is a gobo(or a projection pattern) created by a light valve like a videoprojection of sorts. U.S. Pat. No. 5,829,868, issued Nov. 3, 1998 toHutton, incorporated by reference herein, discloses storing video framesas cues locally in a lamp, and supplying them as directed to the imagegate to produce animated and real-time imaging. A single frame can alsobe manipulated through processing to produce multiple variations.Alternatively, a video communication link can be employed to supplycontinuous video from a remote source.

IPLDs of the prior art use light from a projection lamp that is sentthrough a light valve and focused by an output lens to project images ona stage or a projection surface. The control of the various parametersof the IPLDs is affected by an operator using a central controller. In agiven application, a plurality of IPLDs are used to illuminate theprojection surface, with each IPLD having many parameters that may beadjusted by a central controller to create a scene.

IPLDs used in an entertainment lighting system can produce many colorfulimages upon the stage or projection surface. IPLDs may project imagesonto the projection surface such as still images, video images andgraphic images. The term “content” is a general term that refers tovarious types of creative works, including image-type works and audioworks. Content is typically comprised of still images, video images orloops and computer graphical images.

The Catalyst (trademarked) image projection lighting device manufacturedby High End Systems of Austin Texas incorporates a video projector witha moveable mirror system that directs the images projected by theprojector onto the stage or projection surface. A personal computer isused as a server that provides the images to the projector. A lightingcontroller sends command signals over a communication system to controlthe selection of images from the server to the projector as well ascontrol the various functions of the video projector and the position ofthe image on the projection surface.

During a theatrical presentation the Image projection lighting devicesare often operated in conjunction with theatrical fog generatingdevices. The theatrical fog or smoke generating devices are used tocreate an airborne haze that can be used as a projection surfacecreating three dimensional imagery. The fog generating devices createthe airborne haze by propelling minute particles into the air which canremain suspended in the air for a considerable time. The minuteparticles are commonly created by the fog generating devices byatomization of oils or glycols. The glycol or mineral oil particles(referred to herein as fog particles) can each range in size frombetween twenty microns to below 0.1 micron.

When lighting devices such as image projection lighting devices containcomplex optical and electronic components the fog particles may be drawnthough the cooling system and may condense on the various opticalcomponents diffusing the projected image or shortening the life of thecomponents. If a video projector is used for a component of the imageprojection lighting device, the video projector may often contain afilter system of its own. The filter system of the video projectoroffers very little protection for fog particles since most videoprojector filters rarely are effective on particles below ten micronssuch as those found in fog particles. Sanyo Electronics (trademarked) ofOsaka, Japan has offered a filter cabinet called the Aircleanpro(trademarked) that uses an electrostatic air filtering system forimproved operation of video projectors in cigarette smoke. Unfortunatelya large percentage of fog particles are comprised of particles below tenmicrons since the airborne particles are in a continuous state ofevaporation and electrostatic filters are not effective on theseparticles. There is a need to provide an image projection lightingdevice with a cooling filtration system that provides a high efficiencyof filtration of fog particles below ten microns and that can provide agreater protection to the components of the image projection lightingdevice.

SUMMARY OF THE INVENTION

The present invention in one embodiment provides an improved imageprojection lighting device. The image projection lighting device of anembodiment of the present invention can be comprised of a base housing,a yoke, and a lamp housing. The base housing may include or have locatedtherein, a processing system and a communications port. The lamp housingmay include or have located therein, a video projector, anantireflective aperture, a cooling system, and an air filter.

Service information, concerning the image projection lighting device,may be transmitted by the image projection lighting device from thecommunications port to the central controller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a lamp housing and components therein for an imageprojection lighting device (“IPLD”) in accordance with an embodiment ofthe present invention that incorporates a video projector;

FIG. 2 shows an external view of the image projection lighting device ofwhich the lamp housing and components of FIG. 1, and a base housing area part;

FIG. 3 shows a block diagram of components within the base housing ofFIG. 2;

FIG. 4 shows a lighting system using two IPLDs of an embodiment of thepresent invention and a central controller;

FIG. 5 shows all the same components as FIG. 1 except a pressure sensorin FIG. 1 has been replaced with a tachometer sensor; and

FIG. 6 as all the same components as FIG. 5 except a tachometer sensorin FIG. 5 has been replaced with an air flow sensor.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a lamp housing 230 for an image projection lighting device10 (shown in FIG. 2) of an embodiment of the present invention. FIG. 1also shows the yoke 220 that rotationally supports the lamp housing 230and provides a means for tilting the lamp housing 230 in relation to theyoke 220. The motors and bearings that provide the pivotal connection ofthe yoke 220 to the external housing 230 are not shown forsimplification. A video projector 100 with a video projector housing 103is shown mounted within the lamp housing 230. The video projector 100incorporates a zoom and focus lens 102. The video projector 100 containsa projection lamp 108 to create white light that is separated intoseparate colors that are directed towards a light valve 107 or lightvalves (not shown) used to project multicolored images from theprojection lens 102. An aperture or window aperture 240 in the lamphousing 230 for emitting the projected light from the projector 100 ispreferably made of antireflective glass. The window aperture 240provides a relatively air tight seal for the area where the projectedlight exits from the projection lens 102 in the lamp housing 230.Cooling air enters thought the air filter system 160 as pulled in by thefan 162 in the direction of arrow 164 through an inlet 164i of the lamphousing 230 and pressurizes the lamp housing 230. The pressurized air inthe lamp housing 240 enters an air inlet vent 172 of the projector 100and exits the projector air exiting vent 174 though a duct 165 thatdirects the exiting air to the exiting vent 166 in the direction ofarrow 168. An iris shutter 116 is driven by a belt 114 and a motoractuator 112. The motor actuator 112 is connected via wiring 132 to alamp housing interface circuit board 130. The interface circuit board130 provides motor driving signals to the motor actuator 112 (which maybe an iris shutter motor actuator) that with the action of the belt 114operates iris shutter 116 to open and close.

The interface circuit board 130 is shown connected to wiring 134 thatconnects to sensors 170 and 171. The sensor 170 provides signalsrepresentative of the pressure difference between the air pressure P2within the housing 230 and the air pressure P1 outside the housing 230.Inlet ports 170 a and 170 b allow air pressure to enter the sensor 170.Inlet port 170 a is located internal to the housing 230 and may readinternal pressure. Inlet port 170 b is located external to the housing230 and may read external pressure. The sensor 170 may also be, or maybe replaced by, an airflow sensor, but an air pressure sensor ispreferred. Temperature sensor 171 provides signals representative of theexiting air temperature. The sensors 170 and 171 send signals over thewiring 134 to the interface circuit board 130. The interface circuitboard 130 is electrically connected to the wiring 142. Wiring 142travels through the yoke 220 to the base housing 210, shown in FIG. 3,and connects to the lamp housing circuit board and motor drive interface318.

Wiring 138 shown in FIG. 1 is connected to a serial command port 138 aof the video projector 100 that allows the functions of the videoprojector 100 to be remotely controlled by the projector controlinterface 326 of FIG. 3 and a status of the video projector 100 can alsobe transmitted from the video projector serial command port 138 athrough the wiring 138 to the projector control interface 326. Theserial command port 138 a of the projector 100 is used to control thevarious functions of the projector 100 such as on and off switching ofthe projector 100 and or lamp 108 and selecting a video input to theprojector 100. Video inputs may be supplied to video input ports 144 aand 146 a of the projector 100, for example, from devices connected towiring 144 or 146. The serial command port 138 a may also controlfunctions such as to control the color balance of the projector 100,speeds of an internal fan (not shown), the lamp 108 mode, such as normalor economy or any variable lamp output power level by commands receivedat the serial command port 138 a. In addition, Projector status ofservice information may be sent from the serial command port 138 a ofthe video projector 100 via wiring 138, through yoke 220 to theprojector control interface 326, shown in FIG. 3, such as fan speed,lamp hours, the present lamp mode, the internal temperatures and asoftware version for computer software running the projector 100. Lamphour service information describes operating hours on the lamp or thepercentage of hours of lamp life left on the lamp 108. Commands tocontrol the functions of the video projector 100 of FIG. 1 can be sentfrom the central controller 450 shown in FIG. 4 and received by thecommunications ports 311 or 312 shown in FIG. 3 to control the functionsof the video projector 100. These projector control commands received bythe communications ports 311 or 312 are sent to the processor 316, shownin FIG. 3, where in accordance with the operational code stored in thememory 315, these commands are processed and sent to the projectorcontrol interface 326 that in turn sends the commands to the projectorserial command port 138 a, shown in FIG. 1, over the wiring 138 tocontrol the functions of the projector 100. Also service information canbe sent from the projector 100 serial command port 138 a, shown in FIG.1, over the wiring 138 to the projector control interface 326. Thisservice information can then in turn be sent to the processor 316 whereit is processed in accordance with the operational software stored inthe memory 315. This service information can also be sent to thecommunications ports 311 or 312 to be transmitted over thecommunications system to the central controller 450 shown in FIG. 4 andto be viewed by an operator on a display 452. The projector serviceinformation received by the central controller 450 on the display 452can be read by an operator and used to help make decisions as to whenprojector service should occur. As shown in FIG. 1, a cooling fan 162 isconnected by the wiring 140 to the interface circuit board 130. Theinterface circuit board 130 routes driving signals to the fan 162 thatcan control the fan 162 to be on or off as well as variably control aspeed of the fan 162. The fan 162 is located behind an air filter system160 and is used to pull outside air into the lamp housing 230 throughinlet 164i in the direction of arrow 164 through the air filter system160. The air filter system 160, the fan 162, the exit vent 166, and thesensors 170 and 171 are part of a cooling system. A prefilter 160 a isthe air inlet side of the filter system 160 and is exposed to the air onthe outside of the lamp housing 230 and is used to filter the largerparticles above ten microns before the air enters the secondary filtercomponent 160 b of filter system 160. The secondary filter component 160b is located so that filtered air passing through the prefilter 160 apasses though the secondary filter component 160 b before entering aprojector air inlet vent or port 172. The filter system 160 filterscooling air coming into the lamp housing 230 so that the video projector100 is protected from fog particles and debris. It is preferred that theprefilter component 160 a of the filter system 160 be washable for easyservice by a show technician. It is also preferred that the prefilter160 a be of a dark color such as gray or black since this prefilter 160a may be visualized by an observer looking at the housing of the IPLD 10and larger particles such as pyrotechnics debris will be less visible.

The air drawn through the filter system 160 and then through the fan 162is used to bring cooling air to the projector 100. Cooling air is inputto the lamp housing 230 to provide cooling airflow to the inside of thelamp housing 230. The cooling air exits through a vent 166 in thedirection of arrow 168.

Wiring 146 connects to a video input port 146 a of the video projector100 and is routed through the yoke 220 and is connected in theelectronic housing 210, shown in FIG. 3 to the image control 314. Avideo input supplied to the video input port 146 a, by the image control314 via wiring 146 through yoke 220, may be digital or analog such as anRGB (red, green, or blue) signal, component or composite video. Wiring144 connects to an additional video input port 144 a of the projector100, and is routed through the yoke 220, and is connected in the basehousing 210, shown in FIG. 3, to the external connector 344. The wiring146 can be a video coax cable for communicating video signals requiringgreat flexibility since the lamp housing 230 can be repetitivelypositioned to the base housing 210 during a show. It has been found thata coaxial cable constructed of cadmium bronze conductors increases thelife span of the coax cable under flexing conditions. One such coaxcable manufactured with cadmium bronze conductors is part number 7500aand is manufactured by Belden Wire and Cable Company of St. Louis Mo.Wiring 148 provides power to the video projector 100 from an outsidepower source like a power line from the external connector 340 shown inFIG. 3, and through the yoke 220 shown in FIG. 1. Connector 340 isconnected by any suitable means to an AC power source. The motor andlogic power supply 330 also supplies power for the motors such as panand tilt (not shown), the iris shutter motor 112 of FIG. 1, and acontrol system 215, shown in FIG. 3, in the base housing 210.

FIG. 2 shows an external view of the image projection lighting device10. The base housing 210 of FIG. 2 is also shown in FIG. 3. The powerconnector 340 is shown for connecting to a source of power. The externalvideo input connector 344 allows the video input port 144 a of theprojector 100 to be connected to an outside source. External connector350 connects outside communication from a communication system such ascentral control system 450 shown in FIG. 4 to communications port 311.Central control system 450 can operate a plurality of image projectionlighting devices, such as image projection lighting devices 10 and 20 ofFIG. 4. Image projection lighting device 10 may communicate with thecentral control system 450 via the communications port 311, shown inFIG. 3. External connector 352 may connect communication from anadditional communication system, similar to central controller 450 shownin FIG. 4 for operating a plurality of image projection lighting devicesto a second communications port 312. A description of multiplecommunication systems for multiparameter lights and the advantagesthereof is provided in U.S. Pat. No. 6,331,756 entitled “Method andApparatus for Digital Communications with Multiparameter LightFixtures,” which issued Dec. 18, 2001 and in U.S. Pat. No. 6,459,217,entitled “Method and Apparatus for Digital Communications withMultiparameter Light Fixtures”, which issued on Oct. 1, 2001 and thesepatents are incorporated herein by reference in their entirety.

A bearing 225 shown in FIG. 2 allows for panning of the yoke 220 inrelation to the base housing 210. A pan motor (not shown forsimplification) drives the panning of the yoke 220 for rotation inrelation to the base housing 210 and the pan motor is powered by controlsignals from the lamp housing circuit board and motor drive interface318, shown in FIG. 3. The yoke 220 is connected by bearings (not shownfor simplification) to the lamp housing 230. The lamp housing 230 isdriven to rotate in relation to the yoke 220 by a tilt motor (not shownfor simplification). The tilt motor is powered by control signals fromthe lamp housing circuit board and motor drive interface 318 shown inFIG. 3. An antireflective glass aperture 240 is shown in FIG. 2, forexiting the projected light from the lens 102 of projector 100 from thelamp housing 230, shown in FIG. 1.

FIG. 3 is a block diagram of components within the base housing 210 ofthe IPLD 10. A control system 215, shown in FIG. 3, for remote controlof the IPLD 10 may be constructed of at least a processor 316 that maybe termed a processing system and which may include multiple processorsor discrete components that are used to process data. The control system215 of FIG. 3 also may include a separate memory 315 or the controlsystem 215 may include memory which is part of the processor 316. Theexternal circuit board and motor drive interface 318 for sending controlsignals to motors and an image control interface 314 may be included aspart of the control system 215, shown in FIG. 3. External connectors340, 344, 350 and 352 are shown mounted to the base housing 210 forconnecting a source of power, an external video input, and first andsecond communications systems, respectively. Connector 352 connects tocommunications port 312. The connector 352 may be connected to anexternal communications system such as the communications systemincluding components 442, 436 and 438 shown in FIG. 4, wherein thecommunications system may provide address and command signals as well ascontent. The communications port 312 sends the received address, commandsignals and content to the processor 316 where they may be acted upon tocontrol the parameters of the IPLD 10 and provide the content to theimage control 314 to be projected by the projector 100 or to be storedinto the memory 315. The communications port 312 may also be used totransmit content stored in the memory 315 to the communications system,such as the communications system including components 442, 436 and 438shown in FIG. 4, to other IPLDS, such as IPLD 20 shown in FIG. 4, or toa central controller, such as central controller 450, as well astransmit service information to the central controller 450 or a servicedevice. A suitable system, method and apparatus for communicating imagecontent, from a central controller to one or more IPLDs and betweenIPLDs under control of a central controller is described in U.S. Pat.No. 6,605,907 entitled “Method, Apparatus and System for ImageProjection Lighting,” filed Mar. 4, 2002, incorporated herein byreference The connector 350 connects to communications port 311. Theconnector 350 may be connected to an external communications systemproviding address, commands and content such as the communicationssystem including components 442, 436 and 438 of FIG. 4. The address andcommands signals received by the communications port 311 are sent to theprocessor 316 where they may be acted upon to control the parameters ofthe IPLD 10 of an embodiment of the present invention. Thecommunications port 311 may also transmit data to the communicationssystem, such as the system of FIG. 4, including components 442, 436 and438, such as service information. Service information data transmittedover the communication system may be the projector lamp life, the statusof the air filter system 160, the internal temperatures of the projector100 or the lamp housing 230, the serial number of the projector 100, theversion number of the operating code stored in the memory 315 or theversion of the operating code stored in the projector 100. Thecommunications ports 311 and 312 may be individual devices acting ascommunications ports or they may be part of the processor 316. Thecommunications ports 311 and 312, each may be any device connected to anexternal communications system for receiving and transmitting digitalcommands and transferring digital data.

The processor 316 is connected to the memory 315. The memory 315 may beany type of memory capable of storing information. The memory 315 maycontain the operating system of the IPLD 10 as well as content to beprojected by the projector 100. The processor 316 is connected to theprojector control interface 326. The projector control interface 316 isconnected to the serial command port 138 a of the video projector 100.When the appropriate commands are received by the communications ports311 or 312 the processor 316 may act in accordance with the operatingsoftware stored in the memory 315 by sending command signals to theprojector control interface 326 to operate various functions of theprojector 100. The processor 316 may also receive from the projectorcontrol interface 326 service information that in turn the processor 316forwards to the communications port 311 or 312 for transmission over acommunications system, such as the communications system includingcomponents 438, 436 and 442, to a central controller, such as centralcontroller 450, or other receiving device requiring the desiredinformation.

The image control system 314 is connected to the processor 316. Theimage control system 314 provides video output to the projector 100, viathe wiring 146. The image control system 314 may be a computer videocard used for the manipulation of the content before it is projected bythe projector 100. The image control system 314 is capable ofmanipulation of pixel maps created by the content that is received bythe image control system 314. The processor 316 may receive variouscommands over a communications system through communications ports 311or 312 to alter the content. The content may be altered by the imagecontrol system 314 in various ways such as rotation of the image,keystone correction, image intensity, and as well as independent controlof the pixels for the separate colored images that form a colored image.

As shown in FIG. 3, the processor 316 is also connected to a displaydriver 320 for providing image control of a multicolor video displaydevice 360. The multicolor video display device 360 is preferably an LCDmulticolored display capable of displaying multicolored images of thecontent stored in the memory 315 or the content sent over acommunications system, such as the communications system includingcomponents 438, 436 and 442 of FIG. 4, through one or both ofcommunications ports 311 or 312. It is desirable that the multicolorvideo display device 360 be capable of displaying content for thepurpose of programming IPLD parameters as well as what content will beprojected by the projector 100. As shown by FIG. 3, an input keypad 364is connected to a control input interface 322. The input keypad 364 isused by an operator or lighting director to control the parameters ofthe IPLD 10 of an embodiment of the present invention and select whatcontent is to be projected by the projector 100 as well as selectingwhat content is previewed on the multicolored video display device 360.The control input interface 322 sends the commands inputted through theinput keypad 364 to the processor 316 where they can be acted upon basedon the operational software stored in the memory 315. The input keypad364 and the multicolor video display device 360 can be components of astand alone control system or controller.

The lamp housing circuit board and motor drive interface 318 is shownconnected to the processor 316 in FIG. 3. The interface 318 providescontrol signals to the motors used for pan and tilting of the lamphousing 230 in relation to the base housing 210 and the yoke 225, shownin FIG. 2 (connections and motors not shown for simplification). Theinterface 318 provides control signals to the motor actuator 112, shownin FIG. 1 through interface circuit board 130. The lamp housing circuitboard and motor drive interface 318 also sends to the processor 316information provided by the sensors 170 and 171 via interface circuitboard 130 and wiring 134 shown in FIG. 1. The lamp housing circuit boardand motor drive interface 318 controls the fan 162 to be on or off andwith variable speed through the interface circuit board 130, and throughwiring 140.

FIG. 4 shows a lighting system 400 and IPLDs 10 and 20. The IPLD 20 maybe the same as the IPLD 10 in accordance with an embodiment of thepresent invention. The central controller 450 is shown and is comprisedof a video display device 452, an input keypad 454 and input devices456. A communications cable 436 is shown connected between the centralcontroller 450 and a communications interface 438. The communicationsinterface 438 is shown connected by communication cable 442 to IPLD 10and by communication cable 446 to IPLD 20. IPLD 10 is shown projectingon a projection surface 420 and the projection field is indicated bydashed lines 10 a and 10 b. IPLD 20 is shown projecting on a projectionsurface 420 and the projection field is indicated by dashed lines 20 aand 20 b. Although only two IPLDs are shown for the lighting system 400of FIG. 4 many more IPLDs can be interconnected to form the lightingsystem, such as lighting system 400.

The filter system 160 of the lamp housing 230 shown in FIG. 1 can becomesaturated with debris and fog particles over a period of time with usageof the IPLD 10. The prefilter 160 a may be preferably constructed of anopen cell foam. The prefilter 160 a can be used to capture dust frompyrotechnics that are often used in rock stage shows. The prefilter 160a can be integrated with the secondary filter 160 b and the filtersystem 160 may not have a detachable prefilter 160 a in which case theentire filter system 160 can be disposable. The prefilter 160 a ispreferably detachable from the secondary filter system 160 b. Theprefilter 160 a also helps to protect larger debris from loading thesecondary filter 160 b. The secondary filter 160 b is preferablyconstructed of a glass mat type filter media fabricated of glass fibers.The secondary filter 160 b is preferably at least 99.97% efficient at0.3 microns as standardized by standards 52.1, 52.2 and 62 of ASHRAE(American Society of Heating, Refrigerating, and Air-ConditioningEngineers) located in Atlanta Ga. This filter is also known as a hepafilter (high efficiency particulate air filter). The secondary filter160 b filters out most of the fog particles above 1 micron so thatprimarily only a very low percentage of submicron particles are able topass through the secondary filter 160 b and into the lamp housing 230.

The fan 162 pulls the outside air through the filter system 160 andpressurizes the lamp housing 230 that contains the projector 100. Thepressurized air is received by the projector inlet vent 172 where itprovides cooling air to the projector 100. The projector cooling airexits the projector exit air vent 174 and travels through duct 165 whereit is directed towards the exit vent 166 to the outside air. The lamphousing 230 that contains the projector 100 may be an injection moldedhousing with several service access doors (not shown). The access doorsmay not be air tight. It is important to make sure that the air pressureshown as P2 in FIG. 1 within the housing 230 is greater than the outsideair pressure shown as P1. If the lamp housing 230 does not containpressurized air then it is possible that the projector 100 that may alsocontain a cooling system may draw air through the projector inlet vent172 that is not filtered by the filter system 162. Instead, if the lamphousing 230 is not pressurized with filtered air as provided by thefilter system 160, the projector 100 may pull unfiltered air from theoutside though leaks created by the access door crevices or other minuteopenings found in the lamp housing 230.

The air pressure P2 in the lamp housing 230 is sensed by air pressuresensor 170. The air pressure sensor 170 may contain a first port 170 afor sensing pressure P2 internal to the lamp housing 230 as created bythe fan 162 and the filter system 160. The air pressure sensor 170 mayalso contain a second port 170 b for sensing the pressure P1 outside ofthe lamp housing 230. One type of usable pressure sensor is thepiezoelectric pressure sensor manufactured by Honeywell Sensing andControl of Freeport Ill. The sensor 170 converts the sensed pressures atP1 and P2 to electronic signals that are sent along wiring 134 to theinterface circuit board 130. The interface circuit board 130 iselectrically connected to the wiring 142. Wiring 142 travels through theyoke 220 to the base housing 210, shown in FIG. 3, and connects to thelamp housing circuit board and motor drive interface 318. The lamphousing circuit board and motor drive interface 318 is shown connectedto the processor 316 in FIG. 3. The processor 316 can receive theelectronic pressure signals generated by sensor 170 and in conjunctionwith the operational code stored in the memory 315 determine thecondition of the filter system 160 and cooling system pressure P2.

In operation, the pressure P2 of the lamp housing 230 should be higherthan the outside pressure P1. The filter system 160 as it is exposed tofog particles starts to saturate with the fog particles or “load”. Thefilter system 160 can be said to have various conditions throughout thelife of the filter system 160 such as unloaded (new filter), partiallyloaded or fully loaded (clogged filter) or anything in between. As thefilter “loads” the pressure P2 inside of the lamp housing 230 isreduced. The reduction of pressure P2 inside of the lamp housing 230when compared to the outside pressure P1 as sensed by the sensor 170directly indicates the loading of the filter system 160. As the pressureP2 in the lamp housing 230 is determined by the processor 316 and theoperational code stored in the memory 315 to be reduced below an optimumpressure value, the fan 162 can have its speed increased by theprocessor 316 to compensate for the loading filter system 160. Byincreasing the speed of the fan 162 the pressure in the lamp housing 230can be increased to the optimum pressure value as determined by theoperational code stored in the memory 315 and electronic signals fromthe sensor 170.

At some point the fan 162 may have its speed fully increased andtherefore may not be able to further compensate for the loaded filtersystem 160. When the processor 316 in conjunction with the operationalcode stored in the memory 315 has determined that the fan is at thehighest possible speed and the filter system has loaded to a point wherethe optimum pressure P2 of the lamp housing 230 is no longer attainablea service filter alert (also referred to as Service Filter) can be sentby the processor 316. The filter service alert signal can be sent overthe communication system to the central controller 450 of FIG. 4. Sincea filter is not likely to be changed during a performance event inprogress the electronic pressure values as determined by the sensor 170may be stored in the memory 315 of FIG. 3. This way the status of thefilter system 160 can be determined by the processor 316 from the memory315 and communicated over the communications system, including 442, 436and 438, upon the next initialization (power up) of the product or by arequest command from the central controller 450. The filter alert mayalso be sent to the multicolor video display device 360 of FIG. 3 or theIPLD 10 may be instructed by the processor 316 to provide a visualfilter alert by varying a parameter of the IPLD 10 that can be observedby an observer. For example the IPLD 10 may project images from theprojector 100 of FIG. 1 during the initialization of the IPLD 10 toproject a red color with the text “filter alert” or “service filter” orany text, graphics or colors to be observed by an operator or technicalperson on the projection surface 420 show in FIG. 4 that warns theoperator or technical person that the filter 160 is in need of service.The initialization process, starting up or homing up of the IPLD 10occurs just after the IPLD 10 shown in FIG. 4 is connected to power. TheIPLD 10 of FIG. 4 may also simply refuse to operate normally afterinitialization by for example not projecting light or images on theprojection surface 420 of FIG. 4 from projector 100 to bring attentionto the operator that there is a need for service. By refusing to operatenormally, the IPLD 10 will bring the needed attention to the operatorbefore the performance event starts. The IPLD 10 may also display othertypes of service alerts one of which could be a filter service alert onthe multicolor video display device 360.

Various filter service alert notifications or conditions of filter 160to a technician (also referred to as an operator in this text) may becommunicated by the processor 316 such enabling an audible sound causedby a sound transducer of the IPLD 391 of FIG. 3, enabling a pilot lampof the IPLD 390, projection of an image by the projector 100, displayingthe alert on the display 360, communicating to the console 450 so thatit can be displayed on the monitor 452 or the IPLD refusing to operateor operating unexpectedly. A filter service alert is any notification toa technician or an operator that a filter such as filter system 160, orone of the components 160 a or 160 b, may need to be serviced orreplaced without requiring a visual inspection of the filter system 160by a technician. Upon startup of the IPLD 10 the processor 316 mayreceive electronic pressure signals from the sensor 170. If the pressureP2 of the lamp housing 230 is not at optimum pressure the processor 316may lock out the projector 100 operations so that the lamp 108 in theprojector 100 may not be struck or operated. This will bring to theattention of the operator the need for service of the filter system 160.If the pressure P2 in the lamp housing 230 is below an optimum value theIPLD will not operate correctly or project images.

If the processor 316 determines that the lamp housing pressure P2 iscritically low it is possible to increase the pressure P2 by operatingthe lamp 108 of the projector 100 at a reduced or economy mode. This canbe accomplished with the processor 316 sending control signals to theprojector control interface 326, shown in FIG. 3, that command theprojector 100 to change the lamp mode to a reduced lamp power level.When the projector 100 is operating its lamp 108 at a reduced powerlevel the fans (not shown) in the projector 100 can operate at a reducedspeed thus requiring a reduced airflow entering into projector air inlet172. By reducing power to the lamp 108 in the projector 100 and theprojector 100 requiring less airflow the pressure P2 in the lamp housing230 may be increased even with a loaded filter. This may allow atechnician or operator of a show enough time to complete a show withouthaving the IPLD 10 shut down or stop projecting.

With the IPLD of an embodiment of the present invention the fan 162speed is regulated by the loading of the filter system 160. With anunloaded filter system 160, the fan 162 should have its speed reduced toa minimum to maintain the optimum pressure P2. With a loaded filtersystem 160 the fan 162 will have its speed increased to maintain theoptimum pressure P2 of the lamp housing 230. For shows where the IPLD 10is subject to minimum or no fog particles and as such reduced filterloading, the speed of the fan 162 will also be at minimum reducing thedistraction of noise.

Alternatively there are other sensing techniques that could be used todetect the status of the filter in the IPLD 10. FIG. 5 shows all thesame components as FIG. 1 except the pressure sensor 170 has beenreplaced with a tachometer sensor 162t that is attached to the fan 162to measure the rotational speed of the vanes. If the fan 162 inputvoltage and current are known then we can expect a certain rotationalspeed of the fan 162 based upon the vacuum created by the filter system160. For example if the filter system 160 is removed from the IPLD 10 inFIG. 5 the fan 162 at a known voltage and current (power level) willspin at a slower rate or revolutions per minute (RPM). This is becausethe fan 162 spins slowly with more airflow. The tachometer sensor 162 tcan provide information via wiring 134 to the processor 316 as to thespeed of rotation of the vanes of the fan 162. By using operational codestored into the memory 316 as to what RPM the fan 162 is expected tooperate at a given fan power input power level the condition of thefilter system 160 can be determined. For example at a known input powerlevel a slow fan speed (RPM) can extrapolated to indicate “no filter”.If the processor 316 in conjunction with the operational code stored inthe memory 315 determine based upon revolutions per minute (RPM) of thefan 162 that no filter is in place the IPLD 10 may not be allowed tofunction normally until a service technician installs the correctfilter.

The RPM of the fan 162 can also be used by the processor 316 todetermine that a filter system 160 is in place as this will increase fanspeed at a known fan input power level as determined by the processor316 in conjunction with the operational code stored in the memory 315.If the speed of the fan (RPM) should increase to a rate beyond theexpected rate of an unloaded (or new filter) then a “service filter”alert can be determined by the processor 316 working in conjunction withthe operational code stored in the memory 315. If the speed of the fan162 increases even further it can determined by the processor 316working with the memory 315 that the IPLD 10 may need to be shut down orrefuse to operate normally as the filter system 160 is fully loaded orthe filter system 162 may be blocked. The processor 316 may compare thespeed of the fan 162 to a known input power level to determine if filtersystem 160 is in place, if a filter system 160 needs service, thecondition of the filter system 160 and if the filter system 160 is fullyloaded. The tachometer 162t may be a component of the fan 162 or thetachometer 162 t may be a separate component.

A different technique for determining the condition of the filter mayuse a different sensing technology. FIG. 6 shows all the same componentsas FIG. 5 except the tachometer sensor 162 t of FIG. 5 has been replacedby an air flow sensor 162 f. The air flow sensor 162 f may be an airflow sensor such as the D6A sensor available from Omron (trademarked)Electronic Schaumburg Ill. The sensor 162 f can send electronic signalsrepresenting the air flow from the fan 162 to the processor 316 overwiring 134. The processor 316 in conjunction with the operational codestored in the memory 315 can determine if the filter system 162 is inplace, the condition of the filter system, or if the filter system 162is fully loaded. If the airflow is determined to be higher than areference point stored in the operational code of the memory 315, theprocessor 316 can determine that no filter system 162 is in place. Ifthe airflow is determined by the processor 316 to be at a referencepoint then the filter system 160 can be determined to be in place andunloaded (new filter). If the airflow drops below the reference pointthe processor 316 in conjunction with the memory 315 can determine thata service filter alert needs to be provided. If the airflow continues todrop and reaches a value that is determined by the processor 316 inconjunction with the operational code stored in the memory 315 to be toolow then the processor 316 may send a control signal to the projectorcontrol 326 to shut off the projector 100. The processor 316 working inconjunction with the operational code stored in the memory 315 canreport the condition of the filter system 160 to an operator ortechnician. The reported condition of the filter system 160 of the IPLD10 could be visualized on the display 360, projected on to theprojection surface 420 by the projector 100, sent over thecommunications system to be read by an operator of the centralcontroller 450 or the condition could be reported by pilot lights oraudio tones such as lamp 390 or transducer 391, shown in FIG. 3.

In yet another variation of how to determine the condition of the filtersystem 160, the operating current of the fan 162 can be sensed as avalue at a known operating voltage by the processor 316 working inconjunction with the operational code stored in the memory 315. Anunloaded filter system 160 allows more air flow to be pulled by the fan162 therefore the current required by the fan 162 is higher. If thefilter system 160 is fully loaded the fan 162 will have difficultymoving air and the fan 162 will operate closer to a vacuum. Since thefan 162 is not moving as much air the current required is lower. Bysensing the current requirements of the fan 162 at a known voltage theprocessor 316 working with the operational code stored in the memory 315can determine the filter system 160 condition. The processor 316,working in conjunction with the operational software in the memory 315,can determine no filter, unloaded filter and loaded filter.

Various filter service alert notifications or other conditions of filtersystem 160 to a technician (also referred to as an operator in thistext) may be communicated by the processor 316 such as an audible soundcaused by a sound transducer of the IPLD 391 of FIG. 3, a pilot lamp ofthe IPLD 390, projection of an image by the projector 100, displaying analert on the display 360, communicating to the console 450 so that itcan be displayed on the monitor 452 or the IPLD 10 refusing to operateor operating unexpectedly. A filter service alert is any notification toa technician or an operator that a filter system, such as filter system160, may need to be serviced or replaced without requiring a visualinspection of the filter system 160 by a technician.

The condition of the filter system 160 can be stored into the memory315. This allows a filter service alert to be sent from the IPLD 10 ofFIG. 4 to the console 450 so that an operator of the console may bealerted by the console display 452. The IPLD 10 by using the appropriatesensing technology can alert a technician by any suitable means that thefilter system 160 is not in place and the condition of the filter system160 therefore avoiding damage to the projector 100 or the shut down ofthe projector or lamp 108 during a show.

1. A stage lighting apparatus comprising: an image projection lightingdevice for operation in theatrical fog comprising: a base housing; ayoke; a lamp housing; wherein the lamp housing is positionable inrelation to the yoke by a motor; wherein the yoke is positionable inrelation to the base by a motor; a processing system; and acommunications port; the lamp housing comprising: a video projector, afilter system which has a first inlet and wherein the filter system iscomprised of a first cooling fan, a first air filter and a second airfilter, the video projector comprising: a video projector housing with asecond air inlet a second cooling fan, a light valve, and a lamp,wherein cooling air external to the lamp housing enters the lamp housingthrough the first air inlet to pass through the first air filter to forma first filtered air; wherein the first filtered air is passed throughthe second air filter to form a second filtered air; wherein the firstair filter filters theatrical fog particles greater than ten microns;wherein the second air filter filters theatrical fog particles greaterthan one micron; and wherein at least a portion of the second filteredair is passed through the second air inlet to provide cooling air forthe video projector.
 2. The stage lighting apparatus of claim 1, whereinthe first air filter is a prefilter that filters pyrotechnic particles.3. The stage lighting apparatus of claim 2 wherein the first air filteris a washable filter.
 4. The stage lighting apparatus of claim 1 whereinthe second air filter is comprised of glass mat.
 5. The stage lightingapparatus of claim 4 wherein the second air filter is at least 99.97%efficient at 3 microns.
 6. The stage lighting apparatus of claim 1wherein the second air filter is a hepa filter.
 7. The stage lightingapparatus of claim 1 wherein the first air filter is an open cell foamfilter.
 8. The stage lighting apparatus of claim 1 wherein the first airfilter is detachable from the second filter.
 9. The stage lightingapparatus of claim 1 wherein the first air filter is fixed to the secondair filter so that the first air filter can not be detached from thesecond air filter.
 10. The stage lighting apparatus of claim 1 wherein acommunication as to a status of the filtration system is sent by theprocessor from the communications port over a communications system to acentral controller.
 11. The stage lighting apparatus of claim 1 whereina communication as to a status of the filtration system to a technicianis accomplished by projecting an image from the lamp housing of theimage projection lighting device.
 12. The stage lighting apparatus ofclaim 1 further comprising a monitor display device; and wherein themonitor display device is a component of the base housing; and wherein acommunication as to a status of the filtration system to a technician isaccomplished by the technician viewing the monitor display device. 13.The stage lighting apparatus of claim 1 further comprising a pilot lamp;and wherein a communication as to a status of the filtration system to atechnician is accomplished by the technician viewing the pilot lamp. 14.The stage lighting apparatus of claim 1 further comprising a soundtransducer; and wherein a communication as to a status of the filtrationsystem to a technician is accomplished by the technician listening to asound emitted by the sound transducer.
 15. A stage lighting apparatuscomprising: an image projection lighting device for operation intheatrical fog comprising: a base housing; a yoke; and a lamp housing;wherein the lamp housing is positionable in relation to the yoke by amotor; wherein the yoke is positionable in relation to the base housingby a motor; further comprising a processing system; a communicationsport; and a display device; the lamp housing comprising: a cooling fan,a first air inlet, a first air filter, a lamp, and a light valve; thebase housing comprising a video monitor display device; wherein thecooling fan, the air first inlet and the first air filter together format least part of a filtration system for filtration of theatrical fogparticles; wherein cooling air external to the lamp housing enters thelamp housing through the first air inlet to pass through the first airfilter to form a first filtered air; and wherein a first communicationas to a status of the first air filter to a technician is accomplishedby the technician viewing the video monitor display device.
 16. Thestage lighting apparatus of claim 15 wherein a second communication asto the status of the first air filter to the technician is accomplishedby projecting an image from the lamp housing of the image projectionlighting device.
 17. The stage lighting apparatus of claim 15 furthercomprising a pilot lamp; and wherein a second communication as to astatus of the first air filter to a technician is accomplished by thetechnician viewing the pilot lamp.
 18. The stage lighting apparatus ofclaim 15 wherein a second communication as to the status of the firstair filter is sent by the processor from the communications port over acommunications system to a central controller.
 19. The stage lightingapparatus of claim 15 further comprising a second air filter and thesecond air filter is washable.
 20. The stage lighting apparatus of claim19 wherein the second air filter is comprised of an open cell foam. 21.The stage lighting apparatus of claims 15 wherein the first air filteris a glass matt filter.
 22. The stage lighting apparatus of claim 15wherein the first air filter substantially filters theatrical fogparticles greater than one micron.
 23. The stage lighting apparatus ofclaim 15 wherein the first air filter is at least 99.97% efficient infiltering particles at or below three tenths of a micron.